Constants quiz

What does the following program print?

long long l; 
#include <stdio.h> 
int main() 
{ 
  l = -0x80000000; 
  printf(\%lld"  l); 
} 
$ gcc t.c && ./a.out  

And this one? (beware trick question)

long long l; 
#include <stdio.h> 
int main() 
{ 
  l = -2147483648; 
  printf("%lld"  l); 
} 
$ gcc t.c && ./a.out  

What "it's too difficult!"? Okay here is a hint in the form of a third question:

long long l; 
#include <stdio.h> 
int main() 
{ 
  l = -2147483648; 
  printf("%lld"  l); 
} 
$ gcc -std=c99 t.c && ./a.out  

You are probably reading this on a computer on which the answers are "2147483648" "2147483648" and "-2147483648".